<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>天气案例-深度监视</title>
    <script src="../js/vue.js"></script>
</head>
<body>
    <div id="root">
        <h2>今天天气很{{info}}</h2>
        <button @click="changeWeather">切换天气</button>
        <h3>a的值是:{{numbers.a}}</h3>
        <button @click="numbers.a++">点我让a+1</button>
        <h3>b的值是:{{numbers.b}}</h3>
        <button @click="numbers.b++">点我让b+1</button>
    </div>
</body>

<script>
    const vm=new Vue({
        el:'#root',
        data:{
          isHot:true,
          numbers:{
            a:1,
            b:1
          }
        },
        computed:{
            info(){
                return this.isHot?'炎热':'凉爽'
            }
        },
        methods:{
            changeWeather(){
                this.isHot=!this.isHot
            } 
        },
        //也可以监视info
        watch:{
            isHot:{
                immediate:true,//初始化时让handler调用一下

                //handler调用：当isHot发生改变的时候
                handler(newValue,oldValue){
                    console.log(newValue,oldValue)
                }
            },
            numbers:{
                deep:true,
                //handler才有监视的功能，不要忘记写该函数
                handler(){
                    console.log('number中有内容被改变了')
                }
            }              
        }
    })
</script>

</html>